吸光光度法（紫外/可见光谱）讲座（11）
<H3 style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 16.0pt; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">――提高吸光光度法灵敏度和选择性的某些途径</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-bidi-font-size: 16.0pt; mso-font-kerning: 0pt"><?xml:namespace prefix = o /><o:p></o:p></SPAN></H3>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%; mso-layout-grid-align: none"><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt"> <o:p></o:p></SPAN>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%; mso-layout-grid-align: none"><B><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">2 </SPAN></B><B><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">双波长吸光光度法</SPAN></B><B><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt"><o:p></o:p></SPAN></B>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 24pt; LINE-HEIGHT: 150%; mso-layout-grid-align: none; mso-char-indent-count: 2.0; mso-char-indent-size: 12.0pt"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">由于传统的单波长吸光光度测定法要求试液本身透明，不能有混浊，因而当试液在测定过程中慢慢产生混浊时就无法正确测定。单波长测定法对于吸收峰相互重叠的组分或背景很深的试样，也难于得到正确的结果。此外，试样池和参比池之间不匹配，试液与参比液组成不一致均会给传统的单波长吸光光度法带来较大的误差。如果采用双波长技术，就可以从分析波长的信号中减去来自参比波长的信号，从而消除上述影响，提高方法的灵敏度和选择性，简化分析手续，扩大吸光光度法的应用范围。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt"><o:p></o:p></SPAN>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 24pt; LINE-HEIGHT: 150%; mso-layout-grid-align: none"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">双波长吸光光度法是将光源发射出来的光线，分别经过两个可以调节的单色器，得到两束具有不同波长</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">(</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">λ<SUB><SPAN lang=EN-US>1</SPAN></SUB></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">、</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">λ<SUB><SPAN lang=EN-US>2</SPAN></SUB></SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">)</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">的单色光，利用斩光器使这两束光交替照射到同一吸收池，然后测量并记录它们之间吸光度的差值ㄓ</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">A</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">。若使交替照射的两束单色光</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">λ<SUB><SPAN lang=EN-US>1</SPAN></SUB></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">、</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">λ<SUB><SPAN lang=EN-US>2</SPAN></SUB></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">强度都等于</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">I<SUB>0</SUB></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">，则</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt"><o:p></o:p></SPAN>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">－</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">lg</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">（</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">I<SUB>1</SUB> / I<SUB>0</SUB></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">）<B>＝</B></SPAN><B><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">A</SPAN></B><B><SUB><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">λ<SPAN lang=EN-US>1</SPAN></SPAN></SUB></B><B><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">＝</SPAN></B><B><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">ε<SUB>λ<SPAN lang=EN-US>1</SPAN></SUB><SPAN lang=EN-US>bc＋A</SPAN></SPAN></B><B><SUB><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">s</SPAN></SUB></B><B><SPAN lang=EN-US style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt"><o:p></o:p></SPAN></B>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">－</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">lg</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">（</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">I<SUB>2</SUB> / I<SUB>0</SUB></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">）<B>＝</B></SPAN><B><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">A</SPAN></B><B><SUB><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">λ<SPAN lang=EN-US>2</SPAN></SPAN></SUB></B><B><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">＝</SPAN></B><B><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">ε<SUB>λ<SPAN lang=EN-US>2</SPAN></SUB><SPAN lang=EN-US>bc＋A</SPAN></SPAN></B><B><SUB><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">s</SPAN></SUB></B><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt"><o:p></o:p></SPAN>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 24pt; LINE-HEIGHT: 150%; mso-layout-grid-align: none"><B><SPAN lang=EN-US style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">A</SPAN></B><B><SUB><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">s</SPAN></SUB></B><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">为光散射或背景吸收，若</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">λ<SUB><SPAN lang=EN-US>1</SPAN></SUB></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">和</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">λ<SUB><SPAN lang=EN-US>2</SPAN></SUB></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">相距不远时，</SPAN><B><SPAN lang=EN-US style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">A</SPAN></B><B><SUB><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">s</SPAN></SUB></B><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">可视为相等，则</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt"><o:p></o:p></SPAN>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">－</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">lg</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">（</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">I<SUB>2</SUB> / I<SUB>1</SUB></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">）<B>＝</B></SPAN><B><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">A</SPAN></B><B><SUB><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">λ<SPAN lang=EN-US>2</SPAN></SPAN></SUB></B><B><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">－</SPAN></B><B><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">A</SPAN></B><B><SUB><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">λ<SPAN lang=EN-US>1</SPAN></SPAN></SUB></B><B><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">＝</SPAN></B><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">ㄓ</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt">A<B><o:p></o:p></B></SPAN>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 230.7pt; LINE-HEIGHT: 150%; mso-layout-grid-align: none; mso-char-indent-count: 19.15; mso-char-indent-size: 12.0pt"><B><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">＝（ε<SUB>λ<SPAN lang=EN-US>2</SPAN></SUB>－ε<SUB>λ<SPAN lang=EN-US>1</SPAN></SUB>）<SPAN lang=EN-US>bc<SPAN style="mso-spacerun: yes"> </SPAN></SPAN></SPAN></B><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt"><o:p></o:p></SPAN>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 24pt; LINE-HEIGHT: 150%; mso-layout-grid-align: none; mso-char-indent-count: 2.0; mso-char-indent-size: 12.0pt"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">上式说明，试样溶液在波长</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">λ<SUB><SPAN lang=EN-US>1</SPAN></SUB></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">和</SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">λ<SUB><SPAN lang=EN-US>2</SPAN></SUB></SPAN><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">处吸收的差值，与溶液中待测物质的浓度呈正比关系。这就是应用双波长吸光光度法进行测定的依据。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt"><o:p></o:p></SPAN>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 24pt; LINE-HEIGHT: 150%; mso-layout-grid-align: none; mso-char-indent-count: 2.0; mso-char-indent-size: 12.0pt"><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: ^Times New Roman^; mso-font-kerning: 0pt; mso-hansi-font-family: ^Times New Roman^">双波长测定法对混合组分分别定量时，一般是测定两个波长处的吸光度差，因此方法本身不能提高测定灵敏度。但是，用双波长法进行单组分测定时，如果选择显色剂的极大吸收波长和配合物的极大吸收波长作测定使用的波长对，由于形成配合物而降低之显色剂的吸收值直接加合在所形成的配合物的吸收上，使得配合物的表观摩尔吸光系数显著增加，这样使测定的灵敏度有所提高。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; mso-font-kerning: 0pt"><o:p></o:p></SPAN>
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